It's not bad advice to not reuse that bucket for "regular" beers anymore. Nonetheless, it's reusable. Give it a good scrub with a non-scratch sponge and hot alkaline cleanser, to get the biofilm off the walls and bottom. Then scrub it again. After rinsing well, fill it with an extra-strength solution of bleach or iodophor. Let it sit overnight. Rinse well, and you're good to go. You'll likely still have some non-sacc cells lingering in the bucket, but no more or less than in your "regular" beer fermenters.